Conventionally, a solid-state image pickup element typified by a CMOS image sensor is provided in an image pickup apparatus such as a digital still camera or a digital video camera.
FIG. 1 is a cross-sectional view of a conventional and general solid-state image pickup element.
This solid-state image pickup element 10 includes an on-chip lens 11, a color filter 12, a light-shielding unit 13, a sensor unit 14, and the like, which are laminated in this order from a light incident side. Further, in the case where the on-chip lens 11 is made of an inorganic film having a high refractive index, such as SiN, a planarization layer 15 for removing a difference in level in the color filter 12 is provided between the on-chip lens 11 and the color filter 12.
In the solid-state image pickup element 10, incident light is concentrated on a lower layer side by the on-chip lens 11 and is incident on the sensor unit 14 via the color filter 12, and photoelectric conversion is performed in the sensor unit 14.
In the general solid-state image pickup element 10, the on-chip lenses 11 corresponding to respective pixels are made of the same material so as to be integrally connected in a transverse direction. With this, as illustrated in FIG. 1, some of light that has been incident on a region corresponding to a certain pixel of the on-chip lens 11 may leak to an adjacent pixel and may be incident on the sensor unit 14 of the adjacent pixel without reaching the sensor unit 14 on which the light should be originally incident. Such a phenomenon leads to reduction in photosensitivity and deterioration of color mixture, and therefore some countermeasure is needed.
In view of this, as a countermeasure against the above phenomenon, the applicant of the present disclosure proposed a solid-state image pickup element in which a groove is provided in a boundary between regions corresponding to respective pixels of on-chip lenses 11 which are integrally formed (e.g., see Patent Literature 1).
FIG. 2 is a cross-sectional view of a solid-state image pickup element in which the above countermeasure is employed.
In this solid-state image pickup element 20, light is totally reflected in a groove 21 in the boundary between the regions corresponding to the respective pixels of the on-chip lenses 11. This makes it possible to prevent incident light from leaking to the sensor unit 14 of the adjacent pixel from the sensor unit 14 of the pixel on which the incident light should be originally incident and to prevent color mixture.